Wireshark-bugs: [Wireshark-bugs] [Bug 5654] dissector for DVB-CI (Common Interface)
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=5654
--- Comment #3 from Martin Kaiser <wireshark@xxxxxxxxx> 2011-02-08 05:11:46 PST ---
Hello Bill,
thanks for your reply.
> I'm wondering if an alternative approach wherein the DVBCI
> bytes are stored in (say) a pcap format file
> (with a special "DVBCI DLT") should be considered.
>
> (A conversion to pcap format can be done quite easily with text2pcap).
>
> (With this approach, only the actual DVBCI bytes would be
> dissected/displayed (without the dummy Ethernet/IP/UDP layers)).
>
> (I think that this is the general approach used by packet-radiotap)
I just played a bit with this approach. It looks easier than sending the data
over UDP and seems to require only few changes to the dissector.
> Before discussing further, it would be helpful to know a bit
> more about how the DVBCI bytes are actually captured.
>
> Are there different solutions ? (different vendors, etc ?)
There's some vendors of commercial capturing tools. The tools I've seen come
bundled with some software that can display and export the captured data.
I was trying to define a simple format, hoping that exported data from the
tools can be converted easily into this format.
Some companies also built their proprietary tools purely for internal use. As
they write their own drivers, it should be feasible to output the captured
information as a pcap file.
> Is additional information available ? (e.g., timestamps ?)
First of all, the tools log the direction of the data transfer (host->module or
module->host). I converted this into a direction byte that I put in front of
the actual data transfer. My idea was to use only one single UDP port. Do you
know of a better way to encode the direction in a pcap file or should I keep
the direction byte? (If we go for pcap files and a new DLT, we should agree on
this before I can apply for a DLT value)
Usually, you have timestamps relative to the beginning of the capture. I
understand that they can be set in a pcap file.
The DVB-CI physical layer consists of 4 registers to access data and status
infos. Some tools can log all access to these registers.
Apart from the command interface, there's a transport stream interface to route
the digital tv data stream through the DVB-CI module. There's tools that can
log infos about changes of this routing.
> Is there a (potential) need for "real-time" tapping (as
> I understand packet-gsmtap provides) ?
> ...
IMHO it would be nice but not essential.
> (Also: I expect other [core] developers may have thoughts on approaches to
> getting DVBCI data into Wireshark).
I'm happy to receive more feedback.
Best regards,
Martin
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